Power battery modules in a power battery pack are commonly connected to each other via copper or aluminum braided wires, lamination guide plates, flat connection sheets or arch connection sheets. Although the braided wire has flexibility, an end of the braided wire needs to be pressed into a connection end, thus resulting in a large contact resistance of the connection end. Moreover, in a complex operation condition with frequent vibrations, the braided wire has low reliability and occupies a large space in a length direction. The lamination guide plate includes more than ten or even tens of layers of copper foils or aluminum foils, and the more than ten or even tens of layers of copper foils or aluminum foils are pressed together at two ends of the lamination guide plate. Due to a larger number of the layers of copper foils or aluminum foils, contact resistances of the two ends of the lamination guide plate are large and the lamination guide plate generally is suitable for a one-dimensional flexible deformation, but not for a three-dimensional flexible deformation. In addition, the lamination guide plate has a complex manufacturing process and a high cost. The flat or arch connection sheet has poor flexibility and vibration resistance, and is easy to be broken because of fatigue.